The present invention relates to a process for producing tubes which comprise a strength imparting tubular body and a tubular lining member covering the inner surface of the tubular body and bonded to the body and which are useful as containers, cores, bobbins, poles and the like.
The terms "inner" and "outer" are used herein and in the appended claims based on the tube produced.
For example, the trunks of containers are produced from a tube which comprises a strength imparting tubular body of paper, a tubular lining member covering and bonded to the inner surface of the tubular body and having a synthetic resin inner surface, and a tubular outer covering member provided around the outer surface of the tubular body, by cutting the tube in a specified length. The container is formed by securing a top closure and a bottom closure to the upper and lower ends of the trunk thus obtained.
The tube is conventionally prepared by helically winding around a mandrel a lining forming sheet in the form of a strip and having at least one synthetic resin surface, with the resin surface positioned inside and with a lap formed between the adjacent portions of the strip, helically winding a strip of body forming thick paper around the winding, further winding a covering forming sheet in the form of a strip around the paper winding, moving the combined winding axially of the mandrel in a direction to remove the winding from the mandrel, and bonding the lapping portions of the strip materials.
With the conventional method described above, however, the combined winding around the mandrel is not smoothly movable axially of the mandrel owing to the friction between the synthetic resin inner surface of the lining sheet, with the result that the synthetic resin is melted by the heat of friction to adhere the lining sheet to the mandrel.